Slide compass

ABSTRACT

A direct reading slide compass formed from two molded main components, a body and a slide. The body has a generally rectangular flat central section from which a needle foot depends downwardly and a rotation post extends upwardly. The central section of the body has a transverse slideway formed in its front face within which the slide is adjustable. A marking foot depends from one end of the slide. There is a recess in the rear face of the marking foot which enables the bottom of the central section of the body to pass through the recess and thereby permits a wide range of adjustment of the slide relative to the body while still retaining a long uninterrupted slideway guide surface in the body. Two indicia bearing scales, one in fractions of an inch and the other in decimal portions of an inch, enable the slide to be adjusted relative to a pair of index lines formed on the body.

United States Patent 119 Novak June 17, 1975 SLIDE COMPASS [76] Inventor: Warren D. Novak, 325 Douglas Rd.,

Chappaqua, NY. 10514 [22] Filed: Jan. 9, 1974 [21] Appl. No.: 431,844

Primary Examiner-Samuel B. Rothberg Assistant Examiner-Michael H. Thaler Attorney, Agent, or Firm-Wood, Herron & Evans [57] ABSTRACT A direct reading slide compass formed from two molded main components, a body and a slide. The body has a generally rectangular flat central section from which a needle foot depends downwardly and a rotation post extends upwardly. The central section of the body has a transverse slideway formed in its front face within which the slide is adjustable. A marking foot depends from one end of the slide. There is a recess in the rear face of the marking foot which enables the bottom of the central section of the body to pass through the recess and thereby permits a wide range of adjustment of the slide relative to the body while still retaining a long uninterrupted slideway guide surface in the body. Two indicia bearing scales, one in fractions of an inch and the other in decimal portions of an inch, enable the slide to be adjusted relative to a pair of index lines formed on the body.

16 Claims, 4 Drawing Figures SLIDE COMPASS This invention relates to measuring, drafting, and layout instruments, and particularly to instruments which are adapted for rapidly and efficiently drawing circles or arcs of circles of accurately predetermined size. Throughout this application I will refer to this compass as a drawing or drafting instrument, although it will be understood by those persons skilled in this art that the instrument is readily adapted for other uses with other tools to accomplish differing functions. For example, the marking end of the tool may be fitted with a lead point as illustrated and described herein, or it may be fitted with an ink pen, divider point, carbide point or a knife.

At the present time, two different distinct types or styles of compasses for drawing circles or arcs of circles are available on the commercial market. One type is the very inexpensive and inaccurate instrument which uses a conventional wooden lead pencil as the marking tool. The other type is that which is found in every set of drafting instruments and which usually includes a drop compass for drawing very small circles, a bow compass for drawing slightly larger circles, and a friction locking compass for drawing still larger circles. This latter type or style is suitable for drafting and layout work while the former is generally only suitable for use by children to draw circles of undefined dimensions.

There has been a long standing need for a direct reading drafting instrument to replace the two different styles of compasses identified hereinabove, both of which are indirect reading instruments, e.g., they require the pencil or divider points to be placed against a rule and set to a predetermined dimension. in my issued US. Pat. No. 3,264,736 there is disclosed a direct reading dial compass and in my US. Pat. No. 3,524,258 there is disclosed a direct reading slide compass. Both of these instruments are very precise precision-types of drafting instruments intended to fill the need for a direct reading drafting or layout instrument suitable for use by draftsmen to replace the conventional drop, bow and/or friction locking compasses. The instruments disclosed in those two patents satisfy that need.

In addition to the need for a high quality, precise direct reading compass, there has been and still exists a need for a very inexpensive direct reading compass sufficiently inexpensive to compete with the conventional wooden lead pencil marking compass but sufficiently precise to be useful as a direct reading instrument. The invention of this application is intended to satisfy that need and objective.

Another objective of this invention has been to provide a very inexpensive drafting instrument which is sufficiently accurate to be useful by non-professional draftsmen as a drafting tool to replace conventional drop, bow, and friction locking compasses. The invention of this application is particularly intended to be useful by students for drawing circles or arcs of circles and/or for measuring distances in either an English or metric system, depending upon the scale marked on the instrument and employed by the student.

Generally, the compass which accomplishes these objectives comprises two principal parts, both of which may be molded with sufficient accuracy that machining of these two components is avoided. One of the two principal parts is a combination slide bar and marking foot and the other is a body from which a needle foot extends downwardly and a rotation post extends upwardly. The body has a long transverse slideway in its front face within which the slide bar of the other princi pal part is movable. The slideway is sufficiently long so as to provide a long bearing surface for the slide bar so that even though the bearing surfaces of the two parts are unmachined, there is very little angular play between ti.e two and that play is completely eliminated when a friction locking screw is forced into engagement with the slide bar to lock it in an adjusted position. The long bearing surface within the body also serves as an extended support for the slide, particularly when the slide is fully extended and subject to lateral play or bending. To maximize the range of adjustment, the rear side of the marking foot is recessed so as to enable the bottom of the central section of the body to pass through this recess. This enables the marking foot to be moved through a wide range of adjustment from a position of maximum extension to a position of minimum extension in which the marking foot is located immediately adjacent the center needle.

In the preferred embodiment, the two molded components are made from a medium impact styrene and the locking screw is made from nylon. This choice of material has the requisite strength and dimensional sta bility to be moldable into a compass suitable for the application for which this one is intended. The nylon screw enables the slide bar to be rigidly locked in an adjusted position without any damage to the slide bar caused by the screw.

These and other objects and advantages of this invention will be more readily apparent from the following description of the drawings in which:

FIG. 1 is a front elevational view of a slide compass incorporating the invention of this application.

FIG. 2 is an exploded perspective view of the compass of FIG. 1.

FIG. 3 is a cross sectional view taken on line 33 of FIG. 1.

FIG. 4 is a cross sectional view taken on line 44 of FIG. 1.

Referring first to FIGS. 1 and 2, there is illustrated a preferred embodiment ofa slide compass incorporating the invention of this application. This compass 10 comprises two principal parts, a body 11 and a slide 12. Both ofthese parts are molded and in the preferred embodiment both are molded from a medium impact styrene.

The body 11 comprises a generally rectangular central section 13 from which a rotation post 14 extends upwardly and a needle foot 15 extends downwardly. The rotation post 14 is centrally positioned on the top of the central body section 13 and is surmounted by a knurled handle 16, which in the preferred embodiment is formed as a part of body mold 11. The centerline 17 of the rotation post passes through the center of the central section 13 of the body and through the axis of a needle 18 mounted in the needle foot 15. In the preferred embodiment of the invention, the metal needle 18 is press fit into an aperture 19 molded in the bottom of the foot. This orientation and location of the centerline 17 of the body through the center of the body mold and through the needle axis maintains the balance of the instrument when the handle 16 is twirled or rotated between the thumb and first finger of a person's hand.

In the front face of the central section 13 of the body there is a transverse slideway in the form of a recess which extends transversely across the full width of the central section. This recess is defined by a top wall 21, an undercut rear wall 22, and a bottom wall 23. A slideway lip 24 extends downwardly into the recess from the top wall 21 and a similar lip 25 extends upwardly from the bottom wall. These lips are adapted to receive mating grooves or channels 26, 27 in the top and bottom walls 28, 29 respectively of a slide bar 30. Except for the presence of the grooves 26, 27 in the slide bar 30, it is rectangular in cross section and in the illustrated embodiment is only slightly longer than the width of the central section 13 of the body. The length of the slide bar 30 though may be varied depending upon the application and the intended usage.

At the outer end of the slide bar 30 there is a marking foot 31 of greater thickness T than the thickness T of the slide bar 30. The rear walls of the marking foot 31 and the slide bar 30 are co-planar so that they form a continuous surface 32 as may be seen in FIG. 2. The front wall 33 of the marking foot extends forward a substantial distance from the front wall 34 of the slide bar. This increased thickness of die marking foot strengthens the slide at that point and prevents deflection of the marking foot relative to the slide bar. It also accommodates a recess 35 in the rear wall of the marking foot.

This recess 35 in the marking foot is defined by a top wall 36, a rear wall 37, and a bottom wall 38 in the marking foot. The distance between the top wall 36 and bottom wall 38 of the recess 35 is greater than the distance D between the bottom wall 23 of the recess 20 and the bottom surface 39 of the central section of the body so that the lower section 40 of the central section of the body may pass through the recess 35 when the slide is moved to a position of minimal dimension between a marking lead 41 mounted in the lower end of the marking foot and the needle 18. Consequently, the provision of this recess 35 enables the marking lead 41 to be moved into very close proximity or juxtaposition to the needle 18 while still retaining a long slideway and long guide surfaces for the slide bar.

Immediately above the recess 35 in the marking foot, there is an undercut or recess 42 formed at the head end in the top wall 36 of the marking foot. This undercut or additional recess functions to enable the slide bar to be molded in a conventional die set.

The marking lead 41 is mounted within an inwardly formed extension 45 of the marking foot at the lower end thereof. This inwardly formed extension 45 has a slot 46 extending from the inner face 47 inwardly to a distance slightly more than halfway through the lower end 48 of the marking foot. This slot 46 also has arcuate sections ofa cylinder 49 and 50 formed on its inner end so as to accommodate a cylindrical shaped mark ing lead. To hold the marking lead in an adjusted position in the arcuate sections 49 and 50 of the slot 46, there is a headed screw 52 which extends transversely through the slotted lower end of the marking foot and which has a knurled nut 53 threaded onto its outer end 54. To prevent rotation of the screw 52 within the transverse aperture 51 of the marking foot, a square hub 55 is formed on the screw and is received within a square cross section portion 56 of the transverse aperture 51.

As may b Wen most clearly in FIG. 1, the upper end of the marking foot 31 has a generally rectangular recess 60 formed in its front face. This recess is provided to obtain uniform cross section of the outer end of the arm so as to minimize distortion and eliminate sinking during molding of the item.

To lock the slide bar 30 in an adjusted position within the slideway 20 there is an adjustment screw 61 which extends through a threaded aperture 62 in the rear wall of the central section 13 of the body. This screw has a knurled outer end 63 which enables it to be easily rotated between the thumb and first finger of a persons hand. In the preferred embodiment it is made from nylon so that it frictionally locks the slide bar 30 in an adjusted position when threaded into pressure engagement with it but without damaging or gouging the slide bar.

As may be seen most clearly in FIG. 1, the threaded aperture 62 is located approximately midway between the centerline 17 of the body and the side edge 65. This location is important in order to enable the slide bar to be locked in an adjusted position both when the slide bar is in its outermost extension position or its innermost extension position. In both of these positions the inner end 64 of the screw is still engagable with the rear wall 32 of the slide bar. In either of these positions or in any intermediate position, tightening of the screw 61 against the rear surface of the slide bar has the effect of firmly locking the slide bar in an adjusted position within the slideway. Because the two pieces may be firmly interlocked by the screw 61, the instrument has a very firm feel and there is no tendency of the slide bar to walk or move vertically in the slideway even though there is clearance provided in the slideway between the slide bar and the top and bottom surfaces of the slideway.

Two different scales are printed directly on the front face of the slide bar 30 so that each one may be simultaneously read and compared. In the illustrated embodiment, the lowermost scale is graduated in fractions of an inch with each demarcation indicating onesixteenth of an inch. The uppermost scale is graduated in decimal portions of an inch with each graduation indicating 0.05 inches. In order to facilitate simultaneous reading and possible comparison of the two scales, there are two index marks 72, 73 on the body immediately adjacent the scales. The advantage of these two scales is that they enable a person to simultaneously learn comparative values between fractions and decimals, or, currently most importantly, between the English and the metric system. For example, if an English scale is provided on the lower portion of the slide bar and a metric scale on the upper portion of the slide bar, a student can readily learn the comparative values between the two while using the instrument in the conventional manner for which it is intended.

The primary advantage of the invention disclosed in this application resides in the quality and precision which may be built into a very inexpensive molded component instrument. This inexpensive property enables it to be used as a teaching aid for students, or in applications which would not justify the expense of a very expensive quality drafting instrument.

While I have described only one preferred embodiment of my invention, persons skilled in the art to which it pertains will readily appreciate numerous changes and modifications which may be made without departing from the spirit of my invention. Therefore, I do not intend to be limited except by the scope of the following appended claims:

Having described my invention, I claim:

1. A direct reading slide compass comprising an integral molded body having a generally flat central section, a horizontal slideway formed in the front face of said central section, said slideway having at least one vertical lip extending upwardly into said slideway and at least one vertical lip extending downwardly into said slideway, a rotation post section upstanding from said central section and terminating in an end cap adapted to be rotated between a persons thumb and one finger, a body foot section depending downwardly from said central section and having molded therein at least a portion of a means to receive a center needle, said means to receive said center needle being coaxial with a vertical axis through said rotation post,

a center needle mounted within said center needle receiving means of said body foot section,

an integral molded slide comprising a transverse slide bar adjustably mounted within said slideway and having a marking foot section depending from one end thereof, said slide bar having means cooperable with said lips of said horizontal slideway to hold said slide within said slideway, said marking foot section having molded therein at least a portion of a means to receive a marking element, the upper portion of said marking foot section of said slide being located forwardly of the front face of said central section of said body and having a section extending rearwardly beneath the bottom wall of the central section of said body so as to define a channel in said slide adjacent said slide bar, said channel enabling the lower portion of said central section of said body to pass through said channel without interference between said marking foot section of said slide and said central section of said body so as to maximize the range of adjustment of said slide in said body,

a marking element mounted within said marking element receiving means of said marking foot, said marking element being parallel to said vertical axis through said rotation post,

at least one indicia scale located on the front face of one of said slide bar or said central section of said body, and

an index mark on the front face of the other of said slide bar or said central section of said body.

2. The direct reading slide compass of claim 1 in which said indicia scale is located on the front face of said slide bar and said index mark is located on said central section of said body.

3. The direct reading compass of claim 1 which includes two scales located on the front face of one of said slide bar or said central section of said body, one of said scales being graduated in inches and the other being graduated in centimeters so that a direct comparison of the two different standards may be made in a single setting of the compass.

4. The direct reading compass of claim 3 in which said two scales are both located on the front face of said slide bar, one of said scales being located along the top edge of said slide bar and the other being located along the bottom edge, and said central section of said body having two index marks thereon, one of said index marks being located adjacent the top edge of said slideway and the other index mark being located along the bottom edge of said slideway.

S. The direct reading compass of claim 1 which further includes means to hold said slide bar in an adjusted position in said slideway.

6. The direct reading compass of claim 5 in which said holding means comprises a screw threaded through a threaded aperture in said central section of said body and engageable with said slide bar.

7. The direct reading compass of claim 6 in which said threaded aperture is located in a vertical plane approximately midway between the vertical axis through the rotation post and one side edge of the central section of the body, said one side edge of said central section of said body being located adjacent said one end of said slide bar from which said marking foot depends.

8. The slide compass of claim 7 in which said molded body, said molded slide and said screw are all made of plastic.

9. The slide compass of claim 8 in which said molded body and said molded slide are made from medium impact styrene and said screw is made from nylon.

10. A direct reading slide compass comprising an integral molded body having a generally flat central section, a horizontal slideway formed in one face of said central section, said slideway having at least one vertical lip extending upwardly into said slideway, and at least one vertical lip extending downwardly into said slideway, a rotation post section upstanding from said central section and terminating in an end cap adapted to be rotated between a persons thumb and one finger, a body foot section depending downwardly from said central section and having molded therein at least a portion of a means to receive a center needle, said means to receive said center needle being coaxial with a vertical axis through said rotation post, center needle mounted within said center needle receiving means of said body foot section, an integral molded slide comprising a transverse slide bar adjustably mounted within said slideway and having a marking foot section depending from one end thereof, said slide bar having means cooperable with said lips of said horizontal slideway to hold said slide within said slideway, said marking foot section having molded therein at least a portion of a means to receive a marking element, said means to receive said marking element being parallel to said vertical axis through said rotation post, the upper portion of said marking foot section of said slide being located forwardly of the front face of said central section of said body and having a section extending rearwardly beneath the bottom wall of the central section of the body so as to define a channel in said slide adjacent said slide bar, said channel enabling the lower portion of said central section of said body to pass through said channel without interference between said marking foot section of said slide and said central section of said body so as to maximize the range of adjustment of said slide in said body and the lateral support of said slide by said body when said slide is fully extended,

a marking element mounted within said marking element receiving means of said marking foot,

at least one indicia scale operatively associated and movable with said slide bar, and

an index mark on said bodyv 11. The direct reading slide compass of claim 10 in which said indicia scale is located on the front side of said slide bar and said index mark is located on said central section of said body.

12. The direct reading compass of claim 10 which further includes means to hold said slide bar in an adjusted position in said slideway.

13. The direct reading compass of claim 12 in which said holding means comprises a screw threaded through a threaded aperture in said central section of said body and engageable with said slide bar.

14. The direct reading compass of claim 13 in which said thi :aded aperture is located in a vertical plane approximately midway between the vertical axis through the rotation post and one side edge of the central sec tion of the body, said one side edge of said central section of said body being located adjacent said one end of said slide bar from which said marking foot depends.

15. The slide compass of claim 14 in which said molded body, said molded slide and said screw are all made of plastic.

16. The slide compass of claim 15 in which said molded body and said molded slide are made from medium impact styrene and said screw is made from nylon. 

1. A direct reading slide compass comprising an integral molded body having a generally flat central section, a horizontal slideway formed in the front face of said central section, said slideway having at least one vertical lip extending upwardly into said slideway and at least one vertical lip extending downwardly into said slideway, a rotation post section upstanding from said central section and terminating in an end cap adapted to be rotated between a person''s thumb and one finger, a body foot section depending downwardly from said central section and having molded therein at least a portion of a meAns to receive a center needle, said means to receive said center needle being coaxial with a vertical axis through said rotation post, a center needle mounted within said center needle receiving means of said body foot section, an integral molded slide comprising a transverse slide bar adjustably mounted within said slideway and having a marking foot section depending from one end thereof, said slide bar having means cooperable with said lips of said horizontal slideway to hold said slide within said slideway, said marking foot section having molded therein at least a portion of a means to receive a marking element, the upper portion of said marking foot section of said slide being located forwardly of the front face of said central section of said body and having a section extending rearwardly beneath the bottom wall of the central section of said body so as to define a channel in said slide adjacent said slide bar, said channel enabling the lower portion of said central section of said body to pass through said channel without interference between said marking foot section of said slide and said central section of said body so as to maximize the range of adjustment of said slide in said body, a marking element mounted within said marking element receiving means of said marking foot, said marking element being parallel to said vertical axis through said rotation post, at least one indicia scale located on the front face of one of said slide bar or said central section of said body, and an index mark on the front face of the other of said slide bar or said central section of said body.
 2. The direct reading slide compass of claim 1 in which said indicia scale is located on the front face of said slide bar and said index mark is located on said central section of said body.
 3. The direct reading compass of claim 1 which includes two scales located on the front face of one of said slide bar or said central section of said body, one of said scales being graduated in inches and the other being graduated in centimeters so that a direct comparison of the two different standards may be made in a single setting of the compass.
 4. The direct reading compass of claim 3 in which said two scales are both located on the front face of said slide bar, one of said scales being located along the top edge of said slide bar and the other being located along the bottom edge, and said central section of said body having two index marks thereon, one of said index marks being located adjacent the top edge of said slideway and the other index mark being located along the bottom edge of said slideway.
 5. The direct reading compass of claim 1 which further includes means to hold said slide bar in an adjusted position in said slideway.
 6. The direct reading compass of claim 5 in which said holding means comprises a screw threaded through a threaded aperture in said central section of said body and engageable with said slide bar.
 7. The direct reading compass of claim 6 in which said threaded aperture is located in a vertical plane approximately midway between the vertical axis through the rotation post and one side edge of the central section of the body, said one side edge of said central section of said body being located adjacent said one end of said slide bar from which said marking foot depends.
 8. The slide compass of claim 7 in which said molded body, said molded slide and said screw are all made of plastic.
 9. The slide compass of claim 8 in which said molded body and said molded slide are made from medium impact styrene and said screw is made from nylon.
 10. A direct reading slide compass comprising an integral molded body having a generally flat central section, a horizontal slideway formed in one face of said central section, said slideway having at least one vertical lip extending upwardly into said slideway, and at least one vertical lip extending downwardly into said slideway, a rotation post section upstanding from Said central section and terminating in an end cap adapted to be rotated between a person''s thumb and one finger, a body foot section depending downwardly from said central section and having molded therein at least a portion of a means to receive a center needle, said means to receive said center needle being coaxial with a vertical axis through said rotation post, a center needle mounted within said center needle receiving means of said body foot section, an integral molded slide comprising a transverse slide bar adjustably mounted within said slideway and having a marking foot section depending from one end thereof, said slide bar having means cooperable with said lips of said horizontal slideway to hold said slide within said slideway, said marking foot section having molded therein at least a portion of a means to receive a marking element, said means to receive said marking element being parallel to said vertical axis through said rotation post, the upper portion of said marking foot section of said slide being located forwardly of the front face of said central section of said body and having a section extending rearwardly beneath the bottom wall of the central section of the body so as to define a channel in said slide adjacent said slide bar, said channel enabling the lower portion of said central section of said body to pass through said channel without interference between said marking foot section of said slide and said central section of said body so as to maximize the range of adjustment of said slide in said body and the lateral support of said slide by said body when said slide is fully extended, a marking element mounted within said marking element receiving means of said marking foot, at least one indicia scale operatively associated and movable with said slide bar, and an index mark on said body.
 11. The direct reading slide compass of claim 10 in which said indicia scale is located on the front side of said slide bar and said index mark is located on said central section of said body.
 12. The direct reading compass of claim 10 which further includes means to hold said slide bar in an adjusted position in said slideway.
 13. The direct reading compass of claim 12 in which said holding means comprises a screw threaded through a threaded aperture in said central section of said body and engageable with said slide bar.
 14. The direct reading compass of claim 13 in which said threaded aperture is located in a vertical plane approximately midway between the vertical axis through the rotation post and one side edge of the central section of the body, said one side edge of said central section of said body being located adjacent said one end of said slide bar from which said marking foot depends.
 15. The slide compass of claim 14 in which said molded body, said molded slide anad said screw are all made of plastic.
 16. The slide compass of claim 15 in which said molded body and said molded slide are made from medium impact styrene and said screw is made from nylon. 